Fluoride glasses containing xenon

ABSTRACT

This invention relates to the production of low melting fluoride glasses containing oxidized xenon and, more particularly, to the production of fluoroberyllate glasses containing Xe(VI).

limited States Patent Rieblirig et al.

1451 Mar. 21, 1972 [54] F LUORIDE GLASSES CONTAINING XENON [72] Inventors: Eugene F. Riebling; Paul E. Blaszyk, both of Horseheads; Dennis W. Smith, Corning, all of NY.

[73] Assignee; Corning Glass Works, Corning, NY.

[22] Filed: Feb. 24, -1 969 21 Appl. No.: 801,754

[52] U.S.C| .l ..l06/47 R, 252/62.51,252/301.4 R,

2,511,224 6/1950 Sunetal. ...19 47 2,716,069 8/1955 Pincus 106/47 2,819,977 1/1958 De Paolis 2,901,362 8/1959 Pincus ..l06/47 OTHER PUBLlCATiONS Deutschbein, Otto, Glass for Lasers, Chemical Abstracts, Vol.

69, 1968, 79 884x, abstract of French Patent 1,502,709, 24

Nov. 1967 Primary Examiner-James E. Poer Assistant ExaminerM. Bell AttorneyClarence R. Patty, Jr. and Clinton S. Janes, Jr.

[57] ABSTRACT This invention relates to the production of low melting fluoride glasses containing oxidized xenon and, more particularly, to the production of fluoroberyllate glasses containing Xe(VI).

4 Claims, No Drawings FLUORIDE GLASSES CONTAINING XENON Rare gas compounds were first prepared in 1962 with the discovery of XePtF and XeF In the intervening years to date, many other analogous compounds have been produced, e.g., XeF XeF XeO Na XeO XeO CSZXCFB, RbXeF Rb XeF CsXeF,, CsF'XeOF and 3KF-XeOF Thus, German Pat. No. l,l79,9l7 and US. Pat. No. 3,192,016 describe the preparations of XeF, and XeF respectively. Laboratory studies have demonstrated that some compounds containing hexavalentxenon can be stable up to'about 450 C. In the main, such compounds have contained large alkali metal ions, notably rubidium and cesium, and halides, commonly fluoride and chloride. There appears to be an inverse relationship between cation size (field strength) and a compounds thermal stability for those compounds containing hexavalent xenon [Xe(VI)].

We have now discovered that low melting alkali fluoroberyllate glasses can be prepared which contain oxidized xenon. Many alkali beryllium fluoride base compositions exhibit liquidus temperatures below about 450 C., remain relatively fluid at temperatures between about 450-500 C., and at the same time demonstrate glass forming characteristics resulting from the presence of BeF Therefore, these compositions can provide stable environments for species of oxidized xenon such as Xe(VI), particularly where the alkali metal is one of the large cations Rb or Cs Such glasses may display unusual optical, magnetic, and electrical properties and have been considered for laser applications.

Because of the extreme vaporization of xenon-containing materials at temperatures much above about 500 C., the base glass formulations should exhibit a low viscosity at temperatures below 500 C. We have found that the following base glass forming composition fields will yield relatively fluid melts (less than about 10" poises) at temperatures under about 500 C.: RbFBeF CsF-BeF CsF-RbFBeF CsF- AlF -,-BeF CaF AlF -CsFBeF CsF--CaF BeF and RF and/or RHF TlF and/or TlHF --BeF wherein R consists of Li and/or Na These composition areas provide useful glass matrices for the incorporation of oxidized xenon therein.

We have employed two general methods for making glasses of this invention. The first and preferred method contemplates three steps: XeF is prepared in accordance with known techniques; the solid XeF is reacted with CsF and/or RbF to yield CsXeF and/or RbXeF and, finally, the xenon salt is mixed with and dissolved into the base glass matrix. The second method also comprises three steps: XeF is prepared in accordance with known techniques; the solid XeF is reacted with powdered glass of the desired base composition; and, then the XeF enriched glass is mixed with additional base glass material and melted together.

Various embodiments of our preferred method for manufacturing glasses of this invention are possible. One such em bodiment constitutes vaporizing XeF in a Monel metal chamber and transpiring the vapor onto powdered RbF and/or CsF located in a liquid nitrogen cooled, closed end Kel-F or Teflon reactor. The mixture is heated to about 60 C. to produce the double salt RbXeF, and/or CsXeF-,. The double salt powder is then combined with the base glass in one of three ways: First, the glass batch ingredients are melted together, the melt cooled to a glass and pulverized, and the double salt powder and the glass particles mixed together, heated in a Monel metal or platinum container to a homogeneous melt, and then cooled to a glass. Second, the glass batch ingredients are melted together in a Monel metal or platinum crucible, the double salt powder is heated in a Monel metal or platinum crucible at an elevated temperature lower than the glass melting temperature, the molten glass poured over the salt powder, and then cooled to a glass. Third, the glass batch ingredients are melted together in a Monel metal or platinum crucible, the double salt powder is placed on top of the molten glass, additional molten glass poured over the salt powder, and then cooled to a glass.

These three mixing techniques balance the need to have a relatively fluid base glass melt (for ease of mixing) containing large cations (enhanced thermal stability of the hexavalent xenon) with the need to employ a short mixing time at temperatures since 2Cs XeF-, Cs XeF XeF (gas) at l50-260 C. and Cs XeF 2CsF Xe XeF F at 450-580 C.

The second general method we have utilized in manufacturing glasses of this invention comprises three steps: First, XeF is vaporized in a Monel metal chamber and transpired onto powders of the desired base glass located in a liquid nitrogen cooled, closed end Kel-F or Teflon reactor. Second, the mixture is heated to about 60 C. to react the XeF with large cations and fluoride ions present in the glass surface. Third, the XeF -enriched material is melted in a Monel metal or platinum crucible or mixed with more glass powder and then re-melted in a Monel metal or platinum crucible.

In each of these methods an inert atmosphere such as dry helium, dry argon, or dry nitrogen is required in the heating steps. The time for homogenizing the XeF -containing powder and the base glass at elevated temperatures should not exceed about 10 minutes and, preferably, is less than 5 minutes inasmuch as vaporization and decomposition occur even at the 300 C. melting points of the thallium-containing glasses.

Chemical analyses employing iodometric titration to determine the oxidizing power of Xe(Vl), have demonstrated that glasses containing up to 10 percent by weight of XeF can be produced utilizing the above-recited base glass composition areas. Thus, in the RbF-BeF and CsF-BeF binary systems, good glasses were produced wherein the alkali content ranged about 2040 mole percent RbF or CsF. In the RbFCsF- BeF ternary system, about 90 mole percent BeF, was required with the individual alkali contents having no substantive effect. In the CsFAlF -BeF ternary system, good glasses were found employing about 5l5 mole percent AlF- 10-50 mole percent CsF, and 40-80 mole percent BeF Glasses in the quaternary system CaF --AlF --CsF--BeF were produced utilizing about 5-15 mole percent CaF 5-l 5 mole percent AlF 10-40 mole percent CsF, and 40-80 mole percent BeF In the ternary system CsF-CaF BeF glasses were prepared employing about 20-40 mole percent CsF, 5-l5 mole percent CaF and 50-80 mole percent BeF We were also able to produce glasses in the composition system RF and/or RI-IF TlF and/or TlHF BeF wherein R consists of Li and/or Na, consisting essentially of about l5-35 mole percent RF and/or RHF l530 mole percent TlF and/or TlHF and 4570 mole percent BeF This latter ternary system is particularly useful in the present invention since the softening points ofthe glasses produced can be lower than 300 C. This feature permits the solution of XeF -containing material therein with much less vaporization and decomposition thereof than in the former systems having higher softening points.

Inasmuch as the oxidizing power of Xe(VI) is extremely great, and its propensity for decomposition significantly high, batch ingredients of high purity were utilized in the base glass compositions. Hence, reagent grade CsF, RbF, TlF, BeF etc., were employed to reduce the possibility of incorporating a deleterious contaminant. The batch materials for the TlF and TlHF glasses were melted at temperatures ranging about 350-550 C., whereas the batches for the other glasses required melting temperatures of 500-650 C. The annealing points of glasses within the ternary systems RF-TlFBeF and RI-IF -TlHF BeF were measured as low as 60 C. with softening points at about C. Yet, these glasses were reasonably stable in the ambient atmosphere at room temperature.

Our preferred base glass consists of about 25 mole percent NaHF 25 mole percent TIHF and 50 mole percent BeF The batch materials were melted at 350 C. and the resulting glass was relatively soft at 100 C. with an annealing point of about 60 C. The good fluidity of these glasses at temperatures below 300 C. renders them especially suitable for solution of xeF -containing materials therein.

mole percent BeF 10-20 mole percent RbF and/or CsF and -90 mole percent BeF 10-50 mole percent CsF, 5-15 mole percent MP and 40-80 mole percent BeF 5-15 mole percent CaF 5-15 mole percent AIF 10-40 mole percent CsF, and 40-80 mole percent BeF 20-40 mole percent CsF, 5-15 mole percent CaF and 50-80 mole percent BeF,; and 15-35 mole percent RF and/or RHF 15-30 mole percent TlF and/or TIHF and 45-70 mole percent Bel- 4. An alkali fluoroberyllate glass according to claim 3 containing up to about 10 percent by weight of XeF 

2. An alkali fluoroberyllate glass according to claim 1 having a base glass composition selected from the group consisting of RbF-BeF2, CsF-BeF2, CsF-RbF-BeF2, CsF-AlF3-BeF2, CaF2-AlF3-CsF-BeF2, CsF-CaF2-BeF2, and RF and/or RHF2-TlF and/or TlHF2-BF2 wherein R consists of Li and/or Na .
 3. An alkali fluoroberyllate glass according to claim 2 wherein said base glass is selected from the group of compositions consisting essentially of 20-40 mole percent RbF and 60-80 mole percent BeF2; 20-40 mole percent CsF and 60-80 mole percent BeF2; 10-20 mole percent RbF and/or CsF and 80-90 mole percent BeF2; 10-50 mole pErcent CsF, 5-15 mole percent AlF3, and 40-80 mole percent BeF2; 5-15 mole percent CaF2, 5-15 mole percent AlF3, 10-40 mole percent CsF, and 40-80 mole percent BeF2; 20-40 mole percent CsF, 5-15 mole percent CaF2, and 50-80 mole percent BeF2; and 15-35 mole percent RF and/or RHF2, 15-30 mole percent TlF and/or TlHF2, and 45-70 mole percent BeF2.
 4. An alkali fluoroberyllate glass according to claim 3 containing up to about 10 percent by weight of XeF6. 